In the PROSPER study, eligible patients with nmCRPC, with a PSA doubling time ≤ 10 months, and a PSA ≥ 2 ng/mL at screening, continued androgen deprivation therapy and were randomized 2:1 to either enzalutamide 160 mg or placebo. The primary endpoint was MFS. The study design is shown in figure 1.
Overall 1401 patients were enrolled, with a median age of 74 years. Table 1 demonstrates the demographic and baseline patient characteristics.
In all patients, enzalutamide reduced the risk of metastasis or death by 71% (HR 0.29; 95% CI: 0.24-0.35; p < .0001). A total of 391 patients (28%) had prior definitive surgery, including prostatectomy and cryoablation (n = 246 [26%] in the enzalutamide group, n = 145 [31%] in the placebo group). Notably, Enzalutamide significantly reduced the risk of metastasis or death regardless of whether patients received prior definitive surgery (HR with prior surgery, 0.18; 95% CI: 0.13-0.26; HR without prior surgery, 0.37; 95% CI, 0.30-0.47), as can also be seen in table 2.
Enzalutamide also reduced the risk of metastases or death regardless of whether patients received prior definitive radiotherapy, as can be seen in table 3. The treatment effect was greater in those who received prior radiotherapy.
The authors concluded that in patients with nmCRPC and PSA doubling time less than 10 months, enzalutamide treatment resulted in a clinically and statistically meaningful reduction of metastases development or death. This remained constant regardless of whether patients had received prior definitive therapy (surgery or radiation).
Presented by: Paul R. Sieber, MD, FACS, Lancaster Urology, Lancaster, Pennsylvania
1. Smith MR et al. JCO 2013
2. Hussain M. et al. NEJM 2018
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, @GoldbergHanan, at the 19th Annual Meeting of the Society of Urologic Oncology (SUO), November 28-30, 2018 – Phoenix, Arizona